How to display OpenCV Mat object using Swings?

The class ImageIcon is an implementation of the Icon interface that paints Icons from Images. You can display images on a Swing window using this class, the constructor of this class accepts a BufferedImage object as a parameter.

Therefore to display an OpenCV image that is stored in a Mat object using Swing window, you need to convert it into a BufferedImage object and pass it as a parameter to the ImageIcon method.

Example

import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import org.opencv.core.Core;
import org.opencv.core.Mat;
import org.opencv.core.MatOfByte;
import org.opencv.imgcodecs.Imgcodecs;
public class DisplayingImagesUsingSwings {
   public static void main(String args[]) throws Exception {
      //Loading the OpenCV core library
      System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
      //Reading the Image from the file
      String file = "D:\images\tree.jpg";
      Mat image = Imgcodecs.imread(file);
      //Encoding the image
      MatOfByte matOfByte = new MatOfByte();
      Imgcodecs.imencode(".jpg", image, matOfByte);
      //Storing the encoded Mat in a byte array
      byte[] byteArray = matOfByte.toArray();
      //Preparing the Buffered Image
      InputStream in = new ByteArrayInputStream(byteArray);
      BufferedImage bufImage = ImageIO.read(in);
      //Instantiate JFrame
      JFrame frame = new JFrame();
      //Set Content to the JFrame
      frame.getContentPane().add(new JLabel(new ImageIcon(bufImage)));
      frame.pack();
      frame.setVisible(true);
      System.out.println("Image Loaded");
   }
}

Output

On executing, the above program generates the following output −

Maruthi Krishna

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Updated on: 10-Apr-2020

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